Composite Conductor and Its Preparation Method, Electrical Contact Element

Abstract

The present application discloses a composite conductor, a preparation method thereof, and an electrical contact element, relating to the technical field of conductors. The composite conductor includes a composite powder body and a graphene layer coating the composite powder body, and the material of the composite powder body includes a first metal and a second metal oxide. The composite conductor provided by the present application has good dispersibility and stability, and has high mechanical properties such as hardness and strength.

Description

Technical Field

[0001] The present application relates to the technical field of conductors, and particularly to a composite conductor, a preparation method thereof, and an electrical contact element. Background Art

[0002] With the development of electrical products towards large capacity and small volume, the requirements for electrical contact materials are increasing day by day: the materials are required not to be welded under the conditions of extremely high arc heat and Joule heat, and have good mechanical and electrical wear resistance; there is less metal splash and short arcing time during the breaking process; in a DC environment, it has good anti-welding performance, less material transfer, and low and stable contact resistance.

[0003] Although the currently widely used silver-cadmium oxide electrical contact material has excellent performance, low material cost, and a stable and mature manufacturing process, since metallic cadmium and cadmium salts are harmful to the human body and the environment, the future trend is to gradually reduce and even stop using metal contact materials containing cadmium materials or chemicals. Therefore, finding a new electrical contact material that can replace silver-cadmium oxide has become the focus of current research at home and abroad. Currently, the silver-zinc oxide series of materials is one of the material systems that is expected to replace silver-cadmium oxide materials.

[0004] Due to the excellent thermal properties of zinc oxide, silver-zinc oxide electrical contact materials exhibit excellent anti-welding ability and dominate in the breaking occasions of service currents at all levels of low-voltage electrical appliances. However, the poor wettability between zinc oxide and the silver matrix, as well as the tendency of zinc oxide to agglomerate itself, bring problems such as difficulty in densification and poor dispersion of the second phase. Summary of the Invention

[0005] In view of this, the present application provides a composite conductor, a preparation method thereof, and an electrical contact element.

[0006] An embodiment of the present application is implemented as follows. A composite conductor includes a composite powder body and a graphene layer coating the composite powder body, and the material of the composite powder body includes a first metal and a second metal oxide.

[0007] Correspondingly, an embodiment of the present application also provides a preparation method of a composite conductor, including the following steps:

[0008] Providing a composite powder body, the material of the composite powder body including a first metal and a second metal oxide;

[0009] Growing graphene on the surface of the composite powder body to form a graphene layer coating the composite powder body, obtaining a composite conductor.

[0010] Correspondingly, an embodiment of the present application also provides an electrical contact element, the material of the electrical contact element including the above composite conductor, or including the composite conductor prepared by the above preparation method.

[0011] The composite conductor provided by this application has good dispersibility and stability, and has high mechanical properties such as hardness and strength. Description of the Drawings

[0012] In order to more clearly illustrate the technical solutions in the embodiments of this application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of this application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0013] Figure 1 is a flowchart of the preparation method of the composite conductor provided by the embodiment of this application;

[0014] Figure 2 is a metallographic diagram of the composite conductor provided by Embodiment 1 of this application;

[0015] Figure 3 is a metallographic diagram of the composite conductor provided by Comparative Example 1 of this application;

[0016] Figure 4 is a Raman spectrum diagram of the composite conductor provided by Embodiment 1 of this application. Detailed Embodiments

[0017] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the drawings in the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, rather than all the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of this application. In addition, it should be understood that the specific embodiments described here are only used to illustrate and explain this application, and are not used to limit this application.

[0018] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the drawings; and "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "including" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0019] In this application, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Where A and B can be singular or plural.

[0020] In this application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one (item) among a, b, or c", or "at least one (item) among a, b, and c" can both represent: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can each be single or multiple.

[0021] The various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the described range description has specifically disclosed all possible sub - ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0022] Zinc oxide itself has the characteristic of easy agglomeration, which makes the dispersion of the second phase of the prepared silver - zinc oxide electrical contact material poor, severely restricting the electrical contact performance of the composite material system, mainly reflected in the following aspects: (1) When the oxide particles are severely agglomerated, internal defects in them are prone to form crack sources, thus reducing the anti - damage tolerance of the composite material; (2) Since the conductivity of common oxides differs from that of silver by 6 - 8 orders of magnitude, coarse oxide particles will directly lead to unstable contact resistance; (3) When the dispersion of oxides is poor, it will affect the arc - burning energy and increase the ablation of the electrical contact surface. In addition, in silver - zinc oxide materials, silver and zinc oxide are prone to uneven distribution. This is because during the crystallization process, the chemical components do not have enough time to diffuse, resulting in segregation phenomena, which affect the performance of silver - zinc oxide, such as lower hardness, strength, and elongation of the electrical contact, and the stability needs to be improved.

[0023] The technical solution of this application is as follows:

[0024] In a first aspect, please refer to Figure 1 , an embodiment of this application provides a composite conductor, including composite powder and a graphene layer coating the composite powder, and the material of the composite powder includes a first metal and a second metal oxide.

[0025] It can be understood that the material of the graphene layer is graphene.

[0026] The composite conductor provided by the present application, wherein the composite powder includes a first metal and a second metal oxide, so that the composite powder has high electrical conductivity, anti-welding ability and anti-arc ablation ability. Coating the composite powder with graphene can reduce the segregation of the first metal, reduce the agglomeration of the second metal oxide, and achieve uniform dispersion distribution of each component; coating graphene on the surface of the composite powder, the specific surface area of the composite powder is large, and graphene is uniformly coated on the surface of the composite powder. Increasing the content of graphene is beneficial to further improve the dispersibility of the composite conductor, and enhance the mechanical properties such as hardness and strength of the composite conductor, as well as the stability of the composite conductor.

[0027] In some embodiments, the average particle size of the composite powder is 1 μm to 2 μm, for example, it can be 1.1 μm, 1.2 μm, 1.3 μm, 1.4 μm, 1.5 μm, 1.6 μm, 1.7 μm, 1.8 μm, 1.9 μm, etc.

[0028] In some embodiments, the number of layers of the graphene layer is 2 to 10 layers, for example, it can be 3 layers, 4 layers, 5 layers, 6 layers, 7 layers, 8 layers, 9 layers, etc. Further, the thickness of a single graphene layer can be 0.335 nm to 0.4 nm. In other words, the thickness of the graphene layer can be 0.67 nm to 4 nm.

[0029] In some embodiments, the composite powder is an alloy formed by the first metal and the second metal oxide. In the composite powder, the second metal oxide is dispersed and embedded in the gaps between the first metal tissue particles, playing a strengthening role.

[0030] In some embodiments, in the composite powder, the mass ratio of the first metal to the second metal oxide is (80 - 95):(6 - 25), for example, it can be 95:6.25, 92:12, 88:15, 85:20, 86:16, etc. Within the range of the mass ratio, it is beneficial for the second metal oxide to enhance the electrical contact performance of the first metal.

[0031] In some embodiments, the first metal includes silver.

[0032] In some embodiments, the second metal oxide includes zinc oxide. The second metal oxide provided by the present application does not contain heavy metal cadmium and is non-toxic and environmentally friendly.

[0033] In some embodiments, the composite powder further includes a third metal oxide.

[0034] Further, the third metal oxide includes one or more of nickel oxide and cobalt oxide.

[0035] The mass ratio of the first metal to the third metal oxide is (80 to 95):(0.1 to 0.7), and for example, it can be 87.85:0.19, 87.7:0.38, 87.5:0.64, 80:0.64, 82:0.45, 85:0.5, etc. The third metal oxide is an additive, which is beneficial to improving various properties of the composite powder, such as refining grains and compensating for the anti-material transfer ability of the composite powder. It can be understood that other conventional additives in this field can also be added according to needs.

[0036] Second, please refer to Figure 1 , the embodiment of the present application further provides a preparation method of a composite conductor, including the following steps:

[0037] S11: Provide a composite powder, and the material of the composite powder includes a first metal and a second metal oxide;

[0038] S12: Grow graphene on the surface of the composite powder to form a graphene layer covering the composite powder, and obtain a composite conductor.

[0039] In S11:

[0040] In some embodiments, the preparation method of the composite powder includes:

[0041] S111: Provide a first metal and a second metal, mix them to obtain a pre-alloy powder;

[0042] S112: Provide an oxidant, mix it with the pre-alloy powder to oxidize the second metal to form a second metal oxide, and obtain a composite powder.

[0043] In some embodiments, the second metal includes zinc.

[0044] In some embodiments, the mass ratio of the first metal to the second metal is (80 to 95):(5 to 20), and for example, it can be 87:12.5, 87:13, 89.5:10, 90:10, 91.5:8, 92:8, 93:6.5, 88:12, etc. Within the range of the mass ratio, it is beneficial for the second metal to modify the first metal after being oxidized to form a second metal oxide, and improve the performance of the first metal.

[0045] In some embodiments, the mixing of the first metal and the second metal includes: melting the first metal and the second metal to form a pre-alloy solution, and performing water atomization on the pre-alloy solution to form a pre-alloy powder.

[0046] Melting the first metal and the second metal to form a metal liquid under melting conditions is beneficial for the first metal and the second metal to fully and uniformly contact and mix.

[0047] Furthermore, the temperature of the smelting is 1100°C to 1150°C, and for example, it can be 1105°C, 1110°C, 1115°C, 1120°C, 1125°C, 1130°C, 1135°C, 1140°C, 1145°C, etc. Within the range of the temperature of the smelting, it is beneficial to melt the first metal and the second metal, and the first metal and the second metal with good fluidity are more conducive to contact and mixing.

[0048] The pre-alloy solution can be made into pre-alloy powder by water atomization. The water atomization can be the high-pressure water mist method. Inject the pre-alloy solution into the tundish. Start the high-pressure water pump before injecting the pre-alloy solution to start the workpiece of the high-pressure water atomization device. The alloy solution in the tundish passes through the beam and enters the atomizer through the nozzle at the bottom of the tundish; under the action of the high-pressure water from the atomizer, the pre-alloy solution is continuously broken into fine droplets and falls into the coolant in the device, and the alloy solution solidifies into pre-alloy powder.

[0049] Furthermore, the pressure of the water atomization is 40 Mpa to 45 Mpa, and for example, it can be 41 Mpa, 42 Mpa, 43 Mpa, 44 Mpa, etc. Within the range of the pressure, it is beneficial to efficiently make the pre-alloy solution into pre-alloy powder.

[0050] In some embodiments, the average particle size of the pre-alloy powder is 50 μm to 100 μm, and for example, it can be 55 μm, 60 μm, 65 μm, 70 μm, 75 μm, 80 μm, 85 μm, 90 μm, 95 μm, etc. It should be noted that after preparing the pre-alloy powder by smelting and water atomization, the pre-alloy powder with the required particle size can be obtained by sieving.

[0051] In some embodiments, the oxidant includes oxygen.

[0052] In some embodiments, the mixing of the oxidant and the pre-alloy powder is carried out in an environment of high-pressure oxygen. Specifically, the mixing of the oxidant and the pre-alloy powder can be carried out in an oxidation furnace.

[0053] Furthermore, the oxygen pressure of the high-pressure oxygen is 0.3 Mpa to 0.8 Mpa, and for example, it can be 0.4 Mpa, 0.5 Mpa, 0.6 Mpa, 0.7 Mpa, etc.

[0054] The temperature of the mixing of the oxidant and the pre-alloy powder is 720°C to 800°C, and for example, it can be 730°C, 740°C, 750°C, 760°C, 770°C, 780°C, 790°C, etc.; the time is 8 h to 10 h, and for example, it can be 8.2 h, 8.5 h, 8.8 h, 9 h, 9.2 h, 9.5 h, 9.8 h, etc.

[0055] Thus, under the condition of mixing the oxidant and the pre-alloyed powder, it is beneficial for the second metal to contact the oxidant and form the second metal oxide.

[0056] In some embodiments, when the first metal and the second metal are mixed, a third metal is further added. The third metal includes one or more of Ni and Co.

[0057] The mass ratio of the first metal to the third metal is (80-95):(0.05-0.5), and for example, it can be 87.85:0.15, 87.7:0.3, 87.5:0.5, 80:0.5, 82:0.35, 85:0.4, etc.

[0058] The third metal is mixed with the first metal and the third metal together to form a pre-alloyed powder, and during the reaction with the oxidant, the third metal reacts with the oxidant to form a third metal oxide.

[0059] In some embodiments, after the oxidant is mixed with the pre-alloy to oxidize the second metal to form the second metal oxide, a prefabricated composite powder is formed; the prefabricated composite powder is pulverized to obtain a composite powder.

[0060] Furthermore, the average particle size of the prefabricated composite powder is 80 μm to 150 μm, and for example, it can be 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, etc. It can be understood that, compared with the pre-alloyed powder, oxygen is introduced into the prefabricated composite powder, so the average particle size is slightly larger than that of the pre-alloyed powder.

[0061] In some embodiments, the method for pulverizing the prefabricated composite powder is jet milling.

[0062] Furthermore, the gas source for the jet milling includes one or more of nitrogen and carbon dioxide.

[0063] The air pressure for the jet milling is 0.7 Mpa to 0.9 Mpa, and for example, it can be 0.72 Mpa, 0.75 Mpa, 0.78 Mpa, 0.8 Mpa, 0.82 Mpa, 0.85 Mpa, 0.88 Mpa, etc.

[0064] The gas flow rate for the jet milling is 7 m 3 / min to 10 m 3 / min, and for example, it can be 7.5 m 3 / min, 8 m 3 / min, 8.5 m 3 / min, 9 m 3 / min, 9.5 m 3 / min, etc.

[0065] The time of the air jet milling is 30 min to 60 min, and can be, for example, 35 min, 40 min, 45 min, 50 min, 55 min, etc.

[0066] Thus, under the above conditions of air jet milling, composite powder with the required particle size can be obtained. Moreover, air jet milling is beneficial to the uniformity of the composite powder, and a composite powder without component segregation can be obtained, enabling the first metal and the second metal oxide to be in uniform contact. Air jet milling can also increase the surface area of the composite powder, which is beneficial to the subsequent coating of graphene. Air jet milling does not require the participation of liquid, can avoid the generation of waste liquid, is pollution-free and more environmentally friendly. Air jet milling is carried out at room temperature or lower temperature, which can avoid the thermal decomposition loss of materials.

[0067] In step S12:

[0068] Growing graphene on the surface of the composite powder can be achieved by conventional methods in the art, such as CVD chemical vapor deposition method.

[0069] In some embodiments, growing graphene on the surface of the composite powder includes:

[0070] S121. Place the composite powder in an inert atmosphere and heat it to a first temperature;

[0071] S122. Introduce a carbon source, keep it warm and then cool it down to form a graphene layer coating the composite powder.

[0072] In some embodiments, placing the composite powder in an inert atmosphere includes: performing at least one evacuation and inert gas introduction treatment on the environment where the composite powder is located in sequence. Evacuation can remove the residual gas in the environment where the composite powder is located and the adsorbed gas on the surface of the composite powder. Introducing inert gas can exchange the impurity gas that has not been completely removed, providing an inert atmosphere, which is beneficial to the growth of graphene.

[0073] Further, the vacuum degree after evacuation is 10 -4 Pa to 10 -3 Pa, and can be, for example, 2×10 -4 Pa, 3×10 -4 Pa, 4×10 -4 Pa, 5×10 -4 Pa, 6×10 -4 Pa, 7×10 -4 Pa, 8×10 -4 Pa, 9×10 -4 Pa, etc.

[0074] The inert gas includes one or more of argon, helium, neon, krypton, and xenon.

[0075] The temperature for introducing the inert gas is 120°C to 240°C, and can be, for example, 150°C, 160°C, 180°C, 200°C, 220°C, etc. The time for each introduction of the inert gas is 10 min to 30 min, and can be, for example, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, etc. It should be noted that evacuation and introduction of the inert gas can be alternately carried out multiple times. When the inert gas is introduced for the last time, the continuous introduction of the inert gas is maintained until a composite conductor is obtained.

[0076] Further, when the inert gas is continuously introduced, the gas flow rate of the inert gas is 40 sccm to 80 sccm, and can be, for example, 50 sccm, 60 sccm, 70 sccm, etc. Within the range of the gas flow rate, it is beneficial to create a suitable inert atmosphere, provide a suitable air pressure, and promote the growth of graphene.

[0077] In some embodiments, the heating rate is 10°C / min to 20°C / min, and can be, for example, 12°C / min, 14°C / min, 15°C / min, 16°C / min, 18°C / min.

[0078] In some embodiments, the first temperature is 750°C to 880°C, and can be, for example, 760°C, 780°C, 800°C, 820°C, 840°C, 850°C, 860°C, etc. The relatively low first temperature can avoid segregation of metals in the composite powder at high temperatures, and is beneficial to the uniform growth of graphene on the surface of the composite powder, avoiding agglomeration of the composite powder.

[0079] In some embodiments, the carbon source includes a liquid carbon source. Further, the liquid carbon source includes a cyclic compound. The cyclic compound has a large steric hindrance and is relatively difficult to diffuse, and is easy to adsorb and grow graphene on the surface of the composite powder. Especially at the first temperature provided in this application, graphene can grow uniformly on the surface of the composite powder, avoiding agglomeration of the composite powder.

[0080] Further, the cyclic compound includes one or more of benzene and cyclohexane.

[0081] In some embodiments, the flow rate of the introduced carbon source is 10 μL / min to 20 μL / min, and can be, for example, 12 μL / min, 14 μL / min, 15 μL / min, 16 μL / min, 18 μL / min, etc.

[0082] In some embodiments, the time for introducing the carbon source is 10 min to 30 min, and for example, it can be 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, etc.

[0083] Thus, within the range of the flow rate and time for introducing the carbon source, it is beneficial for the carbon source to uniformly grow graphene on the surface of the composite powder, avoiding the accumulation and waste of graphene.

[0084] In some embodiments, the heat preservation time is 10 min to 20 min, and for example, it can be 12 min, 14 min, 15 min, 16 min, 18 min, etc. It should be noted that during the process of introducing the carbon source, the reaction system is also at the first temperature, and the heat preservation refers to maintaining the first temperature after introducing the carbon source.

[0085] In some embodiments, the temperature reduction can be natural cooling.

[0086] This solution uses the composite powder as the coating substrate. The composite powder has a large surface area, enabling graphene to uniformly grow and coat the composite powder, with a high graphene content and facilitating the uniform distribution of the composite powder and graphene.

[0087] In a third aspect, an embodiment of the present application further provides an electrical contact element, and the material of the electrical contact element includes the above-mentioned composite conductor, or includes the composite conductor prepared by the above-mentioned preparation method.

[0088] In some embodiments, the electrical contact element includes an electrical contact.

[0089] In some embodiments, the preparation method of the electrical contact element includes:

[0090] S21. Provide the above-mentioned composite conductor and press it into a green body;

[0091] S22. Sinter the green body to obtain an electrical contact element.

[0092] The preparation method of the electrical contact element provided by the present application is simple and convenient to operate, and has high conductivity. Each component in the composite conductor is uniformly distributed, which is beneficial to improving the hardness, strength, elongation, stability, etc. of the electrical contact element.

[0093] In some embodiments, the pressure for pressing is 130 Mpa to 180 Mpa, and for example, it can be 140 Mpa, 150 Mpa, 160 Mpa, 170 Mpa, etc.; the pressure holding time is 20 s to 30 s, and for example, it can be 22 s, 24 s, 25 s, 26 s, 28 s, etc. Thus, under the pressing conditions, it is beneficial to obtain a uniformly distributed green body, facilitating subsequent sintering.

[0094] In some embodiments, the sintering is carried out in a protective atmosphere, and the protective gas in the protective atmosphere includes one or more of argon and methane.

[0095] In some embodiments, the temperature of the sintering is 850°C to 930°C, for example, it can be 860°C, 870°C, 880°C, 890°C, 900°C, 910°C, 920°C, etc.; the time is 4h to 8h, for example, it can be 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, etc. Thus, under the conditions of the sintering, the rapid growth of grains can be avoided, resulting in pores or blisters in the green body, and the green body can be sintered densely, improving properties such as conductivity and wear resistance.

[0096] It can be understood that after pressing and sintering, the required electrical contact element can be further processed according to actual needs. Exemplarily, when the electrical contact element is an electrical contact, it can be hot-extruded into a wire or strip after sintering, and then the required specification of the wire or strip can be obtained through multiple drawing and annealing processes, and finally processed into an electrical contact of the required shape.

[0097] It should be noted that when the electrical contact element is in the sintering process, the third metal oxide can undergo a reduction reaction to precipitate the third metal. In other words, the materials in the electrical contact element include the third metal.

[0098] The following specifically describes the present application through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0099] Example 1

[0100] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0101] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize the powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and screened through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0102] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750°C, take it out after oxidizing for 10h, crush it, and screen it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0103] Airflow pulverization: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed air classifier, use nitrogen as the gas source, pulverize and classify, the pulverizing air pressure is 0.8 Mpa, and the gas flow rate is 8m 3 / min, with the time being 45 min, silver-zinc oxide composite powder with a uniform particle size of 1 - 2 μm is obtained;

[0104] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas. Keep the temperature at 150 °C for 10 min, and then evacuate to 10 -3 Pa to remove the gas adsorbed on the surface of the powder. Finally, introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and raise the temperature to 800 °C at a rate of 10 °C / min. Keep the argon gas flow rate at 40 sccm all the time during heating; When the temperature rises to 800 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and keep it for 15 min. Then keep it warm for 15 min and start to cool naturally to room temperature. Take out the sample to obtain a composite conductor.

[0105] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0106] Pressing into ingots: Press the above composite conductor into ingots, with a pressure of 170 Ma and a pressure holding time of 20 s to obtain a silver-zinc oxide graphene blank.

[0107] Sintering: Place the above blank in an atmosphere furnace for sintering, use CH4 / Ar mixed gas as the protective atmosphere, sintering temperature 920 °C, time 6 h, to obtain a silver-zinc oxide graphene ingot blank.

[0108] Processing: Hot extrude the silver-zinc oxide ingot blank into wire, and the wire is obtained through multiple passes of drawing and annealing to obtain the required specification of wire. Finally, process it into a rivet-shaped contact through a riveting machine, that is, an electrical contact element.

[0109] Example 2

[0110] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0111] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn = 90:10, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, then atomize and powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, dry it, and screen it through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0112] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation, with oxygen as the oxidant, oxygen pressure 0.6 Mpa, temperature 750 °C. After oxidation for 10 h, take it out, crush it, and screen it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0113] Airflow pulverization: Place the above-mentioned silver-zinc oxide prefabricated composite powder in a fluidized bed air classifier, use nitrogen as the gas source, pulverize and classify. The pulverization air pressure is 0.9 Mpa, the gas flow rate is 7 m 3 / min, and the time is 50 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1-2 μm;

[0114] CVD growth of graphene: Place the above-mentioned silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon. The temperature is 150 °C, and after maintaining for 10 min, evacuate to 10 -3 Pa to remove the gas adsorbed on the powder surface, and finally introduce high-purity argon to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and increase the temperature to 800 °C at a rate of 10 °C / min. The argon always maintains a flow rate of 40 sccm while heating; When the temperature rises to 800 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and continue for 20 min. Then keep the temperature for 15 min and start to cool naturally to room temperature, take out the sample to obtain a composite conductor.

[0115] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0116] Ingot pressing: Press the above-mentioned composite conductor into an ingot, with a pressure of 170 Ma and a pressure holding time of 20 s to obtain a silver-zinc oxide graphene blank.

[0117] Sintering: Place the above blank in an atmosphere furnace for sintering, use a CH4 / Ar mixed gas as the protective atmosphere, the sintering temperature is 920 °C, and the time is 6 h to obtain a silver-zinc oxide graphene ingot blank.

[0118] Processing: Hot extrude the silver-zinc oxide ingot blank into a strip, and the strip is rolled and annealed through multiple passes to obtain a strip with the required specifications, and finally punched into a sheet-shaped contact.

[0119] Example 3

[0120] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0121] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.85:12:0.15, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize and powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0122] Oxidation: Place the above-mentioned silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C, take it out after oxidizing for 10 h, crush it, and sieve it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0123] Jet milling: Place the above-mentioned silver-zinc oxide prefabricated composite powder in a fluidized bed jet mill, use nitrogen as the gas source, crush and classify it. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1-2 μm;

[0124] CVD growth of graphene: Place the above-mentioned silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas. The temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3 Pa to remove the gas adsorbed on the surface of the powder, and finally introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and raise the temperature to 800 °C at a rate of 10 °C / min. The argon gas always maintains a flow rate of 40 sccm while heating; When the temperature rises to 800 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and continue for 15 min. Then keep it warm for 15 min and start to cool naturally to room temperature, take out the sample to obtain a composite conductor.

[0125] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0126] Ingot pressing: Press the above-mentioned composite conductor into an ingot, the pressure is 170 Ma, and the pressure holding time is 20 s to obtain a silver-zinc oxide graphene blank.

[0127] Sintering, place the above-mentioned blank in an atmosphere furnace for sintering, use a CH4 / Ar mixed gas as the protective atmosphere, the sintering temperature is 920 °C, and the time is 6 h to obtain a silver-zinc oxide graphene ingot blank.

[0128] Processing: Hot extrude the silver-zinc oxide ingot blank into a strip, and the strip is rolled and annealed through multiple passes to obtain a strip of the required specification. Finally, it is punched into a sheet-shaped contact.

[0129] Example 4

[0130] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0131] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 93:6.5:0.5, place them in an intermediate-frequency melting furnace for melting and stirring into a uniform alloy solution, then atomize and powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0132] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C. After oxidation for 10 h, take it out, crush it, and sieve it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0133] Airflow crushing: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed air classifier, use nitrogen as the gas source, crush and classify. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1 - 2 μm;

[0134] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon. The temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3 Pa to remove the gas adsorbed on the powder surface, and finally introduce high-purity argon to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and increase the temperature to 800 °C at a rate of 10 °C / min. The argon always maintains a flow rate of 40 sccm during heating; When the temperature rises to 800 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and continue for 15 min. Then keep it warm for 15 min and start to cool naturally to room temperature, take out the sample to obtain a composite conductor.

[0135] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0136] Ingot pressing: Press the above composite conductor into an ingot, with a pressure of 170 Ma and a pressure holding time of 20 s to obtain a silver-zinc oxide graphene blank;

[0137] Sintering: Place the above blank in an atmosphere furnace for sintering, use a CH4 / Ar mixed gas as a protective atmosphere, the sintering temperature is 920 °C, and the time is 6 h to obtain a silver-zinc oxide graphene ingot blank.

[0138] Processing: Hot extrude the silver-zinc oxide ingot blank into a wire. The wire is obtained through multi-pass drawing and annealing to obtain the required specification wire, and finally processed into a rivet-shaped contact by a riveting machine, that is, an electrical contact element.

[0139] Example 5

[0140] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0141] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate-frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize and powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0142] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C, take it out after oxidizing for 10 h, crush it, and sieve it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0143] Airflow crushing: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed jet mill, use nitrogen as the gas source, crush and classify it. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1-2 μm;

[0144] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas, the temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3 Pa to remove the gas adsorbed on the powder surface, and finally introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and heat it at a rate of 10 °C / min to 800 °C. The argon gas always maintains a flow rate of 40 sccm while heating; When the temperature rises to 880 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and keep it for 15 min. Then keep it warm for 15 min and then start to cool naturally to room temperature, take out the sample to obtain the composite conductor.

[0145] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0146] Pressing into ingots: Press the above composite conductor into ingots, with a pressure of 170 Ma and a pressure holding time of 20 s to obtain a silver-zinc oxide graphene blank.

[0147] Sintering: Place the above blank in an atmosphere furnace for sintering, use a CH4 / Ar mixed gas as the protective atmosphere, the sintering temperature is 920 °C, and the time is 6 h to obtain a silver-zinc oxide graphene ingot blank.

[0148] Processing: The silver-zinc oxide ingot blank is hot-extruded into wire. The wire is obtained through multi-pass drawing and annealing to get the wire of the required specification, and finally processed into a rivet-shaped contact, i.e., an electrical contact element, by a riveting machine.

[0149] Example 6

[0150] This example provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0151] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize the powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0152] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C. After oxidation for 10 h, take it out, crush it, and sieve it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0153] Airflow crushing: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed jet mill, use nitrogen as the gas source, crush and classify it. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1 - 2 μm;

[0154] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas. The temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3 Pa to remove the gas adsorbed on the powder surface, and finally introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and increase the temperature to 800 °C at a rate of 10 °C / min. The argon gas always maintains a flow rate of 40 sccm while heating; When the temperature rises to 750 °C, inject benzene into the reaction furnace as a carbon source, control the flow rate at 10 μL / min, and continue for 15 min. Then keep it warm for 15 min and start to cool naturally to room temperature, take out the sample to obtain the composite conductor.

[0155] Correspondingly, this example also provides an electrical contact element, and the preparation method is as follows:

[0156] Ingot pressing: Press the above composite conductor into an ingot, with a pressure of 170 Ma and a pressure holding time of 20 s to obtain a silver-zinc oxide graphene blank.

[0157] Sintering: Place the above billet in an atmosphere furnace for sintering. Use a CH4 / Ar mixed gas as the protective atmosphere. The sintering temperature is 920 °C and the time is 6 h to obtain a silver-zinc oxide-graphene ingot billet.

[0158] Processing: Hot-extrude the silver-zinc oxide ingot billet into wire. The wire is obtained through multi-pass drawing and annealing to get the wire of the required specification, and finally processed into a rivet-type contact, that is, an electrical contact element, by a riveting machine.

[0159] Example 7

[0160] This example provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0161] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize and powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0162] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C, take it out after oxidizing for 10 h, crush it, and sieve it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0163] Airflow crushing: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed air classifier, use nitrogen as the gas source, crush and classify it. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1 - 2 μm;

[0164] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas. The temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3 Pa to remove the gas adsorbed on the surface of the powder, and finally introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, heat it at a rate of 10 °C / min to 800 °C, and the argon gas always maintains a flow rate of 40 sccm during heating; When the temperature rises to 880 °C, inject benzene into the reaction furnace as the carbon source, control the flow rate at 10 μL / min, and continue for 30 min. Then keep it warm for 15 min and start to cool naturally to room temperature, take out the sample to obtain the composite conductor.

[0165] Correspondingly, this example also provides an electrical contact element, and the preparation method is as follows:

[0166] Ingot pressing: Press the above composite conductor into an ingot under a pressure of 170 Ma for a holding time of 20 s to obtain a silver-zinc oxide-graphene blank.

[0167] Sintering: Place the above blank in an atmosphere furnace for sintering. Use a CH4 / Ar mixed gas as the protective atmosphere, with a sintering temperature of 920 °C and a time of 6 h to obtain a silver-zinc oxide-graphene ingot blank.

[0168] Processing: Hot-extrude the silver-zinc oxide ingot blank into a wire. The wire is obtained through multiple passes of drawing and annealing to obtain a wire of the required specification, and finally processed into a rivet-shaped contact, that is, an electrical contact element, by a riveting machine.

[0169] Example 8

[0170] This example provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0171] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize the powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and screened through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0172] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, with an oxygen pressure of 0.6 Mpa and a temperature of 750 °C. After oxidation for 10 h, take it out, crush it, and screen it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0173] Airflow pulverization: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed airflow pulverizer, use nitrogen as the gas source, pulverize and classify it. The pulverization air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1 - 2 μm;

[0174] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon gas. The temperature is 150 °C, and after maintaining for 10 min, evacuate to 10 -3 Pa to remove the gas adsorbed on the powder surface, and finally introduce high-purity argon gas to normal pressure; Heat the CVD reaction furnace, adjust the heating control device, and increase the temperature at a rate of 10 °C / min to 800 °C. The argon gas always maintains a flow rate of 40 sccm while heating; When the temperature rises to 880 °C, inject benzene as the carbon source into the reaction furnace, control the flow rate at 10 μL / min, and continue for 10 min. Then keep it warm for 15 min and start to cool naturally to room temperature, take out the sample to obtain a composite conductor.

[0175] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0176] Ingot pressing: Press the above-mentioned composite conductor into an ingot under a pressure of 170 Ma for a holding time of 20 s to obtain a silver-zinc oxide-graphene blank.

[0177] Sintering: Place the above blank in an atmosphere furnace for sintering, using a CH4 / Ar mixed gas as the protective atmosphere, with a sintering temperature of 920 °C and a time of 6 h to obtain a silver-zinc oxide-graphene ingot blank.

[0178] Processing: Hot-extrude the silver-zinc oxide ingot blank into a wire, and the wire is obtained through multi-pass drawing and annealing to obtain a wire of the required specification. Finally, it is processed into a rivet-shaped contact by a riveting machine, that is, an electrical contact element.

[0179] Embodiment 9

[0180] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0181] Preparation of silver-zinc alloy powder by water atomization: Weigh raw materials according to the mass ratio of Ag:Zn:Co = 87.5:12:0.5, place them in an intermediate frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize and powder them through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and screened through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0182] Oxidation: Place the above silver-zinc alloy powder in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C, take it out after oxidizing for 10 h, crush it, and screen it through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0183] Airflow pulverization: Place the above silver-zinc oxide prefabricated composite powder in a fluidized bed jet mill, use nitrogen as the gas source, pulverize and classify it, the pulverization air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1-2 μm;

[0184] CVD growth of graphene: Place the above silver-zinc oxide composite powder in a CVD furnace, evacuate to 10 -3 Pa to discharge the residual gas in the reaction chamber, then introduce high-purity argon, the temperature is 150 °C, keep it for 10 min and then evacuate to 10 -3Pa is used to remove the gas adsorbed on the powder surface, and finally high-purity argon is introduced until the normal pressure is reached; the CVD reaction furnace is heated, and the heating control device is adjusted to raise the temperature to 800 °C at a rate of 10 °C / min. The argon flow rate is always maintained at 40 sccm while heating. When the temperature rises to 880 °C, benzene is injected into the reaction furnace as a carbon source, and the flow rate is controlled at 10 μL / min for 15 min. Then, after holding for 15 min, it starts to cool naturally to room temperature, and the sample is taken out to obtain the composite conductor.

[0185] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0186] Pressing: The above composite conductor is pressed into an ingot under a pressure of 170 Ma for a holding time of 20 s to obtain a silver-zinc oxide-graphene blank.

[0187] Sintering: The above blank is placed in an atmosphere furnace for sintering. A CH4 / Ar mixed gas is used as the protective atmosphere, the sintering temperature is 920 °C, and the time is 6 h to obtain a silver-zinc oxide-graphene ingot blank.

[0188] Processing: The silver-zinc oxide ingot blank is hot-extruded into a wire. The wire is obtained through multiple passes of drawing and annealing to obtain the wire of the required specification, and finally processed into a rivet-shaped contact by a riveting machine, that is, the electrical contact element.

[0189] Example 10

[0190] This embodiment provides a composite conductor, and the preparation method of the composite conductor is as follows:

[0191] Preparation of silver-zinc alloy powder by water atomization: Weigh the raw materials according to the mass ratio of Ag:Zn:Ni = 87.5:12:0.5, place them in an intermediate-frequency melting furnace for melting and stirring into a uniform alloy solution, and then atomize the powder through a high-pressure water atomization device to obtain a silver-zinc alloy slurry, which is dried and sieved through a 200-mesh sieve to obtain silver-zinc alloy powder;

[0192] Oxidation: The above silver-zinc alloy powder is placed in a high-pressure internal oxidation furnace for oxidation. The oxidant is oxygen, the oxygen pressure is 0.6 Mpa, the temperature is 750 °C, and it is taken out after oxidation for 10 h, crushed, and sieved through a 100-mesh sieve to obtain a silver-zinc oxide prefabricated composite powder;

[0193] Airflow crushing: The above silver-zinc oxide prefabricated composite powder is placed in a fluidized bed air classifier, and nitrogen is used as the gas source for crushing and classification. The crushing air pressure is 0.8 Mpa, the gas flow rate is 8 m 3 / min, and the time is 45 min to obtain a silver-zinc oxide composite powder with a uniform powder particle size of 1 - 2 μm;

[0194] CVD growth of graphene: The above silver-zinc oxide composite powder is placed in a CVD furnace, and the vacuum is pumped to 10-3 The residual gas in the reaction chamber was discharged by Pa, and then high-purity argon was introduced. The temperature was 150 °C, and after maintaining for 10 min, it was evacuated to 10 -3 Pa to remove the gas adsorbed on the surface of the powder. Finally, high-purity argon was introduced until the normal pressure was reached; the CVD reaction furnace was heated, and the heating control device was adjusted to raise the temperature to 800 °C at a rate of 10 °C / min. The argon flow rate was always maintained at 40 sccm during heating; when the temperature rose to 880 °C, cyclohexane was injected into the reaction furnace as a carbon source, and the flow rate was controlled at 10 μL / min for 15 min. Then, after maintaining for 15 min, it was naturally cooled to room temperature, and the sample was taken out to obtain the composite conductor.

[0195] Correspondingly, this embodiment also provides an electrical contact element, and the preparation method is as follows:

[0196] Ingot pressing: The above composite conductor was pressed into an ingot under a pressure of 170 Ma for a holding time of 20 s to obtain a silver-zinc oxide-graphene blank.

[0197] Sintering: The above blank was placed in an atmosphere furnace for sintering, using a CH4 / Ar mixed gas as the protective atmosphere, at a sintering temperature of 920 °C for 6 h to obtain a silver-zinc oxide-graphene ingot blank.

[0198] Processing: The silver-zinc oxide ingot blank was hot-extruded into a wire. The wire was drawn and annealed through multiple passes to obtain a wire of the required specification, and finally processed into a rivet-shaped contact by a riveting machine, that is, an electrical contact element.

[0199] Comparative Example 1

[0200] This comparative example provides the silver-zinc oxide composite powder in Example 1, that is, without graphene grown on the surface.

[0201] Comparative Example 2

[0202] Comparative Example 2 is basically the same as Example 1, except that in Comparative Example 2, the carbon source benzene was replaced with gaseous CH4.

[0203] Comparative Examples 3-4

[0204] Comparative Examples 3-4 are basically the same as Example 1, except that in Comparative Examples 3-4, the temperatures for CVD growth of graphene are 950 °C and 650 °C, respectively.

[0205] Metallographic analysis was performed on the composite conductors of Example 1 and Comparative Example 1, and the metallographic diagrams are as Figure 2 and Figure 3 shown.

[0206] From Figure 2 and Figure 3It can be seen that the graphene-coated composite powder in Example 1 is uniformly dispersed, and its dispersibility is significantly better than that of Comparative Example 1.

[0207] The Raman spectrum test was carried out on the composite conductor of Example 1, and the obtained Raman spectrum is as Figure 4 shown.

[0208] From Figure 4 it can be known that obvious graphene characteristic peaks appear in the Raman spectrum of the composite conductor of Example 1, indicating that in the composite conductor, graphene effectively coats the composite powder.

[0209] The hardness, tensile strength and elongation of the composite conductors of Examples 1 to 10 and Comparative Examples 1 to 4 were measured, and the results are shown in Table 1.

[0210] Among them, the hardness was measured by a Vickers hardness tester; the tensile strength and elongation were tested by a tensile testing machine; the samples were all in the initial state.

[0211] Table 1

[0212]

[0213] As can be seen from Table 1, the average hardness and tensile strength of the composite conductor provided by this application are significantly improved compared with the comparative examples. The elongation of the examples is lower than that of the comparative examples. The lower the elongation, the greater the strength and hardness, and the more difficult it is to extend. This application uses graphene to coat the composite powder to make the organizational structure of the composite conductor uniform, thereby improving the mechanical properties and stability of the composite conductor.

[0214] The technical solutions provided by the embodiments of the present application have been introduced in detail above. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A composite conductor, characterized in that, It includes a composite powder and a graphene layer coating the composite powder, and the material of the composite powder includes a first metal and a second metal oxide; Among them, the first metal includes silver, the second metal oxide includes zinc oxide, and the composite powder is an alloy formed by the first metal and the second metal oxide; Among them, the graphene layer is obtained by CVD growth, and the temperature of the CVD is 750°C to 880°C; the carbon source used in the CVD includes a liquid carbon source, and the liquid carbon source includes a cyclic compound.

2. The composite conductor according to claim 1, wherein, the average particle size of the composite powder is 1μm to 2μm; and / or the number of layers of the graphene layer is 2 to 10 layers.

3. The composite conductor according to claim 1, wherein, in the composite powder, the mass ratio of the first metal to the second metal oxide is (80 - 95):(6 - 25).

4. The composite conductor according to claim 3, wherein The composite powder further includes a third metal oxide; The third metal oxide includes one or more of nickel oxide and cobalt oxide; The mass ratio of the first metal to the third metal oxide is (80 - 95):(0.1 - 0.7).

5. The method for preparing a composite conductor according to any one of claims 1 to 4, characterized in that, It includes the following steps: Provide a composite powder, the material of the composite powder includes a first metal and a second metal oxide, wherein, the first metal includes silver, and the second metal oxide includes zinc oxide; Grow graphene on the surface of the composite powder to form a graphene layer coating the composite powder, and obtain a composite conductor.

6. The preparation method according to claim 5, characterized in that, The preparation method of the composite powder includes: Provide a first metal and a second metal, mix them to obtain a prefabricated alloy powder; Provide an oxidant, mix it with the prefabricated alloy powder to oxidize the second metal to form a second metal oxide, and obtain a composite powder.

7. The preparation method according to claim 6, wherein, the second metal includes zinc; and / or the mass ratio of the first metal to the second metal is (80 - 95):(5 - 20).

8. The preparation method according to claim 6, characterized in that, The mixing of the first metal and the second metal includes: melting the first metal and the second metal to form a prefabricated alloy solution, and performing water atomization on the prefabricated alloy solution to form a prefabricated alloy powder; the temperature of the melting is 1100°C to 1150°C; the pressure of the water atomization is 40MPa to 45MPa; the average particle size of the prefabricated alloy powder is 50μm to 100μm.

9. The preparation method according to claim 6, wherein, the oxidant includes oxygen; and / or the mixing of the oxidant and the prefabricated alloy powder is carried out in a high-pressure oxygen environment; and / or the temperature of the mixing of the oxidant and the prefabricated alloy powder is 720°C to 800°C, and the time is 8h to 10h; and / or after the oxidant is mixed with the prefabricated alloy powder to oxidize the second metal to form a second metal oxide, a prefabricated composite powder is formed; the prefabricated composite powder is pulverized to obtain a composite powder; the method for pulverizing the prefabricated composite powder is jet milling.

10. The preparation method according to claim 9, wherein, The oxygen pressure of the hyperbaric oxygen is 0.3 MPa to 0.8 MPa; and / or The average particle size of the prefabricated composite powder is 80 μm to 150 μm; and / or The gas source for the air jet milling includes one or more of nitrogen and carbon dioxide; and / or The air pressure for the air jet milling is 0.7 MPa to 0.9 MPa; and / or The air flow rate of the air jet milling is 7 m 3 / min to 10 m 3 / min; and / or The time for the air jet milling is 30 min to 60 min.

11. The preparation method according to claim 10, characterized in that, Growing graphene on the surface of the composite powder includes: placing the composite powder in an inert atmosphere, heating to a first temperature; introducing a carbon source, keeping warm and then cooling to form a graphene layer coating the composite powder; wherein, The heating rate is 10 °C / min to 20 °C / min; and / or The first temperature is 750 °C to 880 °C; and / or The flow rate of introducing the carbon source is 10 μL / min to 20 μL / min; and / or The time for introducing the carbon source is 10 min to 30 min; and / or The time for keeping warm is 10 min to 20 min; and / or The carbon source includes a liquid carbon source, the liquid carbon source includes a cyclic compound, and the cyclic compound includes one or more of benzene and cyclohexane.

12. An electrical contact element, characterized in that, The material of the electrical contact element includes the composite conductor according to any one of claims 1 to 4, or includes the composite conductor prepared by the preparation method according to any one of claims 5 to 11.

13. The electrical contact element according to claim 12, characterized in that, The preparation method of the electrical contact element includes: providing the composite conductor, pressing it into a green body; sintering the green body to obtain the electrical contact element; The pressure for pressing is 130 MPa to 180 MPa, and the pressure holding time is 20 s to 30 s; The sintering temperature is 850 °C to 930 °C, and the time is 4 h to 8 h.

Images